RedlineMan

Well Mitch...

This is a real sticky wicket. You are using the Constructive Definition of an apex. This unfortunately varies with every car, driver, and even lap! It says nothing about the situational aspects of that apex, such as how much speed, what entry angle, car setup, etc.

I prefer the strict geometric definition that the apex is the point where you are closest to the inside of the turn. This does not pre-suppose speed, angle, or any other parameter and offers open interpretation for any correct combination of entry parameters (which is almost infinite!!).

If you are going slow, any apex will likely do. If you are going medium to fast, then late is safe. If you are REALLY flying, you might actually be apexing for many feet to yards even.

Yes... I know. We could split this red hair six ways from Sunday. That's why reading all the books on HP driving is more or less useless if you haven't already done it! It aint like the real thing!!!!

Brian P

That reminds me of a quote that was used at our driver's ed meeting:

From Yogi Berra,

Z-man

Thanks again for the great input, guys.

Redline: you got me over-generalizing again! Yes, it is true: apex points differ from track to track, car to car, driver to driver...etc. The high hp car vs. the 'momentum' car I agree make a difference in terms of how/when/where to apex. (Side note: what do you consider to be a slow or 'momentum' car?)

Of course, being an intermediate type driver, I'll stick with mostly late apexes, except for the turns where I'm more comfortable carrying more speed, and there I'll take an earlier apex. (Examples for these corners: T11 at The Glen & South Bend at VIR)

Hmm, I guess I've hijacked my own thread! We we talking about braking, no?!?

-Z-man.

M758

John,
You are right. There alot of folks that just can drive their way out of a paper bag. Most of these guys don't race. A few do and really make it hard for guys trying to get alot from their cars. In my opinion 944-spec racing has done wonders for me. Racing a low HP 131 rwhp momentum car vs similar cars really make you work you tail off. I have alot of guys with much faster car feeling really cool and not getting much more speed from their cars. When you watch them you can see how slow they are in the corners.

Last PCA race I was only a couple ticks off the pace of some well driven F-stock cars.

With respect to lines and braking and such.
I find that most people brake too much and corner too slowly. They simply are not able to approach the limits. It takes along time or a pressure cooker enviroment to find them. Racing lines are always varried. The DE line is taught as the safe one. Not the fast one. In most places it is really not much different, but in critical area it is vastly different.

Phoenix interational is not a tough track, but the two 1-2 area is a little difficult. Turn 1 you come off the gently baking of the main straight turning left. You bounce over a transiton from banking to flat and the car unsettles. Then you head into a decreasing radius left. DE line stays brake moderate for turn 1 and then straightline brake and late apex 2. That works good for DE. Here the important thing to first protect cars by limiting speed in turn 1 and staying off the braks in the transions. Cars have nastiy habit of spining and hitting concrete wall on the inside if still on the brakes. Then of course to late apex 2.

Racing lines much differenet. I infact hardly brake for turn 1 and take it about 95 to 100 mph on full throttle after touch the brakes. (I am working on not touch at all). Then I get on brakes hard and trail brake my way all the way around turn 2. If I want be fast I hold a late apex, but If I want to pass I have stay on the brakes harder too pull it in tight. It kills my speed in to 3 and 4, but will put me in front. The actualy turn in points are different from the DE line and slightly different for each car. There used to be advertising on the oval walls to use a reference, but since these are gone it is really hard and all I can do is go by feel.

I was taking to another racer who was surprised how much faster a competitior in a similar car was. I asked him if he trailed braked in two 2. Said no. I asked why not. He said he the back end of the car did not feel right. I asked if he had spun or overcooked it in turn 2. (Note the is plenty of run off there and space to safely rejoin the track) He said no. I said I have spun and over cooked it there lots of times. That was how I learned how much faster I could go. I told him to try to go deeper and deeper until he went off. Then he would know where the limit was and how slow he was actually going in that corner.

mitch236

Sometimes I wish we were all togther to talk this out. M758, I have to disagree that one needs to spin off to find the limit. You know the limit is reached when you cannot make the apex.

Brian P

I guess spinning is one sure way of knowing that you won't make the apex.

forklift

I have only spun once, and I apexed early and spun at track out....at 90. I had fresh front tires and ...not fresh rear tires...and lifted DOH! live and learn.

Next time back, new rear tires, a little slide, a little throttle, and a little steering input and all went well.

M758

My point is that if you plan on racing and want to win to need to find the limits if the car. That means you need to push more and more. As you do you will at some point attempt to carry some level of speed that may cause you to think you will spin or lose control. If you want to race you will need to over come that fear and simply try it. The result may be a spin or loss of control. You may miss and apex, you may spin, you may of off track straight. If you never to to that point where you are in pure recovery mode you have NOT pushed hard enough. DE is different as you not racing. Why push that hard. In racing it is important. I hate it when I guys wonder why they are slow or think the other guy is cheating and they not taking it to the limit in every corner. There are place on tracks were finding this limit involves great risk. There are other were the worst is quick trip in the grass.

BTW... For those who are so opposed to a slight loss of control how many race? How many are fast in their class?

ColorChange

Mitch and M758: You guys sound good but I repeat, the only war to KNOW you are at the limit is with a DAS. This also avoids the need to blow apexes, or worse, blow the track.

Z-man

IMHO, I don't totally agree with that statement. Sure, a DAS has HUGE benefits to analyze one's driving, but there is a FAR BETTER tool!

I think the BEST tool that one can use to see if they are going around the corner faster is the good all 'sweet cheeks' seat of your pants method. Between your inner ear and 'that place where the sun don't shine,' you have plenty of instantaneous input to know the following:
1. If you're going through a corner faster than before.
2. If you're closer to the limits than before.
3. If your tire grip is fading.
4. The car is understeering or oversteering.
5. Probably 1,000,000 other tiny things that occur whilst driving around a corner!

This feedback is instantaneous. With a G-analyst tool, it can be difficult to remember how you felt when you were at the limit, since the data is review AFTER the event.

The human element plays a huge factor here. Sure, I may not be able to pull imperical numbers out of my butt (pun intended!), but if I am sensitive and understand my car's handling dynamics, I will be able to know right away what's going on.

If a person has progressed to the intermediate level without being able to tell if he's going faster or is nearing the limit without any external devices, then that person will most likely spin sooner than the person who is in tune with his car. If one is not in harmony with his car, then the data from a DAS device is useless. If one IS in harmony with his car, there is no real need for a DAS device.

Again, this is IN MY HUMBLE OPINION,
-Z-man.

mitch236

I wonder how well the DAS system would work with varying elevations where the g-loads can be increased or decreased by downforce.

What is the limit of a corner? That is a very personal thing. Not to name-drop but my neighbor, Justin Bell, who used to have a HPD school at Moroso, can take corners much faster than I can and the car is also much smoother. No matter how I try, his technique and skill is so much better than mine that I cannot compete. So there is alot more than just pushing harder or analyzing. Only seat time and attention to detail will improve you. I also realize that when trying to go faster, spinning is enevitable. Whenever I hear someone say that they have been doing this for years and have never spun, I wonder if either they are lying or slow.

BTW just because you are spinning doesn't mean you should miss the apex!!

Brian P

I'm going to repeat a post because I think it got lost earlier... This was in response to a DAS providing a nice friction circle graph and the ability to use that to tell us whether or not we are at the limit...

Is it really that simple?

Shouldn't the edges of the G-force graph (i.e., the friction circle) change a bunch as we drive around the track? For example, when you are near the top end of a gear, your amount of torque decreases and the amount of acceleration available to you decreases. Similarly, at higher speeds, you will have more braking potential as air resistance alone can slow you down quite a bit.

Also, elevation changes and banking can do wonders at giving your car more G-force capabilities. For example, going through the carousel at Watkins Glen (or the toe of the boot), you get tons of banking in your favor and the friction circle becomes really wide at that point.

If you were then to look at the G-force plot through the downhill left (an off-camber turn) into the laces, you might think that you are always leaving a lot on the table. For example, you might be at the limit there and pulling only .8Gs while in the carousel you could be below the limit and pulling 1.1Gs.

Maybe we can just look at the maximum G-force through that you pulled in that turn (the DL90 software makes that easy) but even then, how do you know if that represents the limit?

ColorChange

Z-man:

It is almost impossible for a driver, even at the Shumi level, to know where he is exactly all the time. For you and I, you really need one. I am talking more advanced than a g analyst (steering angle, throttle position, ...). What this does is allow you to basically calibrate your ***. I keep video and record what I think while I am driving, and then sync my comments to the data. Yes, I talk while I drive. I will say "nailed that at the limit, or blew the entry speed, turned in a little early, hit the apex, 9/10 on trackout ...). When I go back and look at the data, either between sessions, or more often, that night, I see how I was really doing. This allows me to accurately train my bottom to really know what is going on. Without it, you may be close, or not, but you will never know without a DAS.

Mitch,
You are a racer, trying to hit the apex after a spin, that's funny. I can just see you trying to look ahead down the track as the scenery goes spinning by.

If you had Justin drive your car with a DAS you would know exactly what he was doing to beat you. This is exactly my point! DAS rules, but, seat time will be the single biggest benefit for most drivers, after that, perfect practice makes perfect driving, and perfect is only defined by a DAS. Only a DAS.

Z-man

I disagree. Redline stated in an earlier thread that he went close to 10 years without logging a spin at DE's.

Personally, I have 30 track days, and I run in the White (intermediate, no instructor) group. I run mid-pack most of the time. I have no spins in my log book. Am I driving at 8/10th's? Probably more like 6.5 to 7/10ths (of my ability). But my view is that I'd rather build up my speed slowly and cautiously, rather than find my limits after it's too late. Also: I want to focus on being smooth and consistent: those are better goals than wanting to go faster, and trying to find the limits!

As long as I'm not interfering with other driver's by being sooo slow, (And I'm really not THAT slow, despite what folks like Brian P and DrJupeman say), I see no problem in my approach to DE. Will I spin someday? Sure. And I'm not afriad of spinning: I've had the car 'out of control' on the track often enough to know not to panic. (I also autocross, where 1/2 the fun is 'saving' a car that's going to hot into a corner! )

I have a Hey, Wait for Me Racing track shirt that states:


-Z.

ColorChange

Brian and Mitch: For large downforce cars CART, F1 ... this is a big factor but you know it in advance, and can calculate it or build up the data by experience. For our cars and most tracks, the downforce has relatively small effect. For high speed sweepers like the carousel at Road America (110+ mph), it does come into play. You can calculate the limit the g increase, or look at it from historical lap data. Coming into turn 1 after the straight you might push 160+ mph, sure you can see braking increases, but you have to slow to normal speeds to make the turn so the lateral g's are fairly common across most turns (high speed sweepers excluded). Most turns are below 90 and our cars have little aero forces at those speeds. For elevation or camber changes, again, historical lap data shows the limit, or at least shows you the fastest you have ever run it. That is why I recommend getting the best driver you know to “lay the law down” in your car so you know where you are good, and where you suck.